COTS-supported Web-based Interactive Electronic Technical ...



COTS-supported Web-based Interactive Electronic Technical Manual Architecture Using UML

EXTENDED ABSTRACT

Introduction

An Interactive Electronic Technical Manual (IETM) [1], is a package of information and documentation required for diagnosis and maintenance of complex weapon systems and both military and commercial equipment. An IETM is a technical manual prepared in a digital form on a suitable media with the aid of an automated authoring system and designed for electronic screen display to an end user. It possesses the following characteristics:

• Electronic: To enhance comprehension, an IETM contains information that is designed and formatted specifically for screen presentation.

• Interactive: The IETM display system operates interactively as a result of user requests and the associated input information.

• Navigable: The information is hyper-linked; the end user can access the same data via a variety of paths. Information elements can reference other elements within the IETM as well as information sources outside the IETM.

IETMs are authored in a way that allows a user to retrieve and comprehend the required information faster and easier than is possible with a paper technical manual. The intelligent features of the IETM display system provide powerful interactive troubleshooting procedures for users in the field.

The military performance specifications [1, 2] based on SGML [3] define the process and content for authoring and displaying IETMs. The roles of these specifications are:

• MIL-PRF-87268A defines how the IETM should look and behave to the end user.

• MIL-PRF-87269A defines the IETM Data Base (IETMDB) forms, structure, and key controlling mechanisms.

The separation of the IETM database content from the presentation attributes has found favor in IETM system design and development. However, the standardization focus has been on the database structures and the targeted “look and feel” and not on the run-time and presentation version of the IETM. As a result, each software vendor has developed a proprietary system for capturing IETM data and presenting it to the end user. In attempting to maintain a flexible approach to the definition of the IETM database, the specifications nearly guarantee non-portability across different vendor products.

As the use of IETMs as information assets became more widespread and as they incorporated more functionality, it became important to establish an infrastructure to manage and distribute IETM updates to multiple field sites and to provide life-cycle support for numerous IETMs.

In this environment, the fact that differing IETMs cannot interoperate has become a major impediment. Additionally, since a common standard for the structure of the delivered IETM is lacking, it has been exceptionally challenging to define the requirements for, or to make the initial design of, a standard infrastructure to support IETMs in the field [4].

Problem

The IETM community is faced with a requirement to enable interoperability within and among IETM systems. The initial phase of interoperability support has been undertaken by the development of a Joint IETM Architecture (JIA) [4].

The JIA effort is lead by the US Navy out of the Naval Surface Warfare Center Carderock Division with ManTech Advanced Systems as the principal technical support team. The JIA enables user-level interoperability and is based on Commercial Off The Shelf (COTS) Web technologies. The specification for IETM deployment and manipulation on DoD Intranets is the missing component of Web-enabled COTS-supported interoperability for IETMs.

Our main research objective is to develop a standardized Web-enabled COTS-supported alternative to the complex SGML data models within the IETM database specification. The study of the IETM database specification revealed a set of major problems also encountered by other developmental efforts using the same specification [5]:

1. Complexity: The IETM SGML data model resembles a programming language more than a document or database definition.

2. Ambiguity: The SGML-centered specifications in MIL-D-87269A are precise in their prescriptions for the data element contents, but ambiguous with respect to the semantics for handling these elements in an IETM system.

3. Obscurity: The specifications do not realize a technical architecture that is easily recognized and implemented using common practice techniques and client-server technologies.

4. Source data includes information on document behavior: Use of variables, expressions, conditional branching constructs, and context filtering elements introduce dynamic behavior into the IETM data model.

IETM functionality includes a number of features which together enable and control the user's traversal of the IETM structure. Since these functions are performed at presentation time, and are written into the IETM, they can be regarded as software programs (in a high-level language) which control the presentation of the technical information. [7]

XML (Extensible Markup Language) being a simplified subset of SGML designed for Web applications may seem like a solution for the problem at hand. Yet XML is not enough, it provides the ability to capture and transmit IETM self-describing data structures on the Web, but it doesn’t provide a standard mean to interpret behavior information required for document presentation.

Approach

Our core approach to arriving at a COTS-supported, Web-enabled alternative to the IETM database specification began with a comprehensive modeling effort. We choose to view the IETM database specification in an object-oriented fashion. The SGML specification represents the IETM documents by an abstract data model that is centered around the data while an object oriented model encompasses not only the structure of a document, but also the behavior of a document and the objects of which it is composed. Using the Unified Modeling Language (UML) [6], we described our IETM object model static design view as well as its interactions with an IETM display system. Figure 2 shows the UML component diagram for the proposed overall IETM system architecture.

The IETM top-level system architecture is composed of the following components:

User interface

The user interface component is responsible for rendering information on the user side and for handling all user interactions.

IETM Electronic Display System (EDS)

The EDS system receives and handles user’s requests for IETM data access and navigation. It uses context dependent filtering to select the appropriate information for presentation. It also creates IETM document objects based on the IETM object model.

Data access

Reads the IETM content information and process it to produce a document representation according to the interface specification with EDS.

IETM object model

The IETM object model is an implementation of the IETM object model specification. The later identifies the interfaces and objects used to represent and manipulate an IETM document and the relationships between these interfaces and objects. This model is based on the IETM database specification MIL-PRF-87269A.

IETM data

The IETM content information. It can be stored as files or as a database.

We developed the system component-based architecture further by making a breakdown for the top-level architecture components to the level of well-defined components desired to assess the capabilities of Web COTS to support the standard requirements.

Contributions

1. Defining the IETM system in terms of components with well-defined interfaces provides the conceptual foundation for assembling our system out of Web COTS components and for exploring multiple solutions effectively.

2. The IETM object model defined:

a) Isolates the implementation of the IETM content representation and manipulation from the IETM display system, thus achieving interoperability among IETM content providers.

b) Can be implemented in various programming languages and reused to access and manipulate IETM documents not only for display but also for authoring and configuration management purposes.

3. Using UML, we developed expressive models for visualizing, specifying, and documenting the proposed IETM system. These models help us manage system complexity and provide means to forward engineer our system components.

In this paper, we discuss a component-based IETM system architecture, where we identify (candidate/alternative/potential/existing) potential COTS components. We also introduce an alternative to the IETM database specification called the IETM object model, a candidate component for reuse throughout the IETM document lifecycle. We also report our experience using UML to model the IETM system architecture and the IETM object model design.

References

1. Naval Surface Warfare Center, Carderock Division: Data Base, Revisable - Interactive Electronic Technical Manuals, For the Support Of. MIL-PRF-87269A.

2. Naval Surface Warfare Center, Carderock Division: Manuals, Interactive Electronic Technical – General Content, Style, Format, And User-Interaction Requirements. MIL-PRF-87268A.

3. International Organization for Standardization: Information Processing - Text and Office Systems - Standard Generalized Markup Language (SGML). ISO 8879:1986.

4. Eric L. Jorgensen: Proposed Web-Based Joint IETM Architecture (JIA) for the Interoperability of DoD IETMs. , August 1998.

5. Internet MID Demonstration. ManTech Advanced Systems International Inc.,

6. Booch, G., Rumbaugh, J., Jacobson, I.: The Unified Modeling Language User Guide. Addison-Wesley, 1999.

7. Ann M Wrightson: Safety in IETP. IEE Aerospace group symposium on Certification of Ground-Air Systems, London, February 1998.

-----------------------

Don Reynolds

ManTech Advanced Systems International, Inc.

1000 Technology Drive

Fairmont, WV 26554, USA

reynolds@mantech-

Dina Ghobashy, Sherif Yacoub, Hany H. Ammar

Dept. of Computer Science and Electrical Engineering,

West Virginia University,

Morgantown, WV 26506-6109, USA

{ghob, yacoub, ammar}@csee.wvu.edu

Model

IETM Object

Data Services

User Services

Business Services

User Interface

IETM Data

System (EDS)

IETM Electronic Display

Data Access

Figure2 Overall IETM System Architecture

Web Server and Database Interface Technical Description

Links

Runtime

Data

Data Flow

Delivery

Database Server/ Application Server

Runtime

Data

Runtime

Data

[pic]

Authoring Systems

Browser

End User

Component

Software

Component

Software

Encapsulated Object

Infrastructure

Site Server

Web Server

Web Server

Figure1 Joint IETM Architecture

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